1887

Abstract

Velocity variations affect the quality of seismic data and hinder the interpreters from defining both structure and lithology. Structural complexity, particularly in land seismic data, is responsible for both poor imaging and getting mispositioned events in depth. In spite the advances in migration, its ability to provide right depths is quite often limited because of there is a substantial difference between the migration velocity -the best for proper imaging-, and the vertical velocity, used to perform the time-to-depth conversion (depthing). The main reason for this discrepancy is seismic anisotropy, however sometimes it cannot be adecuately included in data processing of complex areas; therefore depthing is still a crucial step in the interpretation process. Several techniques for depthing are based on vertical velocity modeling from different approaches. Using study cases in areas of complex geology, we explain advantages and limitations of the most common methods: 1) Time-Depth “Velocity” Functions, 2) Layer Cake Methods, 3) Laterally-Varying Layer Cake Modeling; and 4) Geostatistical Velocity Modeling. There is no a unique recipe for chosing one of those, but depending on the complexity and availability of high-quality data, different methods can be applied or cobined to obtain better results. Most of the pitfalls come from misunderstanding the type of velocity used for both imaging and depthing. In general, a good velocity model is the one that better honor the data and reproduce the geologic trends at the same time. From the real case studies, we propose Laterally-Varying Layer Cake and Geostatistical velocity models as standar procedures for depthing in Andean complex structures.

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/content/papers/10.3997/2214-4609-pdb.330.172
2012-07-29
2020-09-25
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http://instance.metastore.ingenta.com/content/papers/10.3997/2214-4609-pdb.330.172
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